Data sources

Where our data comes from

Every score, map, and recommendation is built on publicly available government and education datasets. Each source below links to the authoritative provider so you can verify any data point yourself.

Last updated: June 3, 2026

Water-system mapping note

Wherever water quality information is shown, we display: “Mapped to nearest available water system based on public EPA data.” Water-system boundaries do not always align with addresses, so the nearest reporting system is used when an exact match is not available.